Genetic similarity and secondary structure prediction of two cyanobacterial toxins’polyketide synthetases

to investigate the genetic similarity and secondary structure prediction of polyketide synthetases corresponding to microcystins and nodularins, respectively. Gene of polyketide synthase (PKS) from 2 toxin-producing cyanobacteria was prepared by polymerase chain reaction and the gene sequence was analyzed. The gene sequences of PKS from microcystins-producing cyanobacteria and nodularins-producing ones were derived from GenBank. Their sequence identity and phylogenetic similarity of corresponding proteins was analyzed using the software of both DNAStar and phylip. The secondary structure of PKS of Anabaena sp. 202A1/35 and Nodularia spumigena NSOR10 was predicted using the methods of Garnier-Robson and Karplus-Schulz. The Hydrophilic plot and surface probability plot were obtained from Kyte-doolittle and Emini, respectively. The results indicate that the target gene sequences for both microcystin PKS and nodularin PKS share high identity; Phylogenetic analysis suggests close phylogenetic relationships between Anabaena sp., Nostoc sp. and Nodularia sp. There are significant similarities in the secondary structure of the analyzed proteins. Both PKS show similar identical hydrophilicity and surface probability characteristics.